Containers with valves are used for beer, cola and similar popular beverages. The numbers being in circulation are very high and the containers will often be situated in restaurants or similar establishments where many people will come and go.
The containers are normally without any danger to the surroundings. The working pressure is only a few bars, and the containers are dimensioned on the large side to be able to resist this pressure. If a container, however, is exposed to intense heat, which for instance might be the case when a building is burning, the pressure in the container might be so high, that the container will explode.
When these containers are used for foodstuffs they can hardly be supplied with special security valves to blow off at too high a pressure. This is a among other things, due to the fact that an efficiently operating security valve is a rather complicated mechanism with components and inaccessible corners which are liable to resist the cleaning which the containers otherwise are subjected to. Therefore, there will always be a risk that such security valves might be a hotbed of developing, for example, cultures of bacteria which might destroy or poison the beverages being stored in the container.
The double valves, which are mounted on the containers, have a construction which entails that the valves, without being dismounted, can be cleaned efficiently and safely in the same process as the container. The construction entails, however, at the same time, that the higher the pressure in the container rises, the tighter the valve will close. These conventional double valves are therefore not able to secure a container from exploding due to overpressure.
There is thus a need for a double valve which has all the advantages of the conventional double valves and is just as easy to clean, and furthermore is constructed to secure the container from being blow up due to too an overpressure.